Evidence for $D^0 - \bar{D}^0$ Mixing

TL;DR

This paper provides evidence for $D^0 - ar{D}^0$ mixing through lifetime measurements, showing a 3.2 sigma deviation from zero, and finds no CP violation, based on extensive data from the Belle detector.

Contribution

First measurement of $D^0 - ar{D}^0$ mixing using lifetime differences in multiple decay modes with high statistical significance.

Findings

Measured $y_{CP} = (1.31 \pm 0.32 ext{(stat.)} \pm 0.25 ext{(syst.)}) ext{ extperthousand}$

Observed 3.2 sigma evidence for mixing, but no CP violation detected.

Based on 540 fb$^{-1}$ of data from the Belle detector.

Abstract

We observe evidence for $D^0 - \bar{D}^0$ mixing by measuring the difference in apparent lifetime when a $D^0$ meson decays to the CP eigenstates $K^+K^-$ and $\pi^+\pi^-$, and when it decays to the final state $K^-\pi^+$. We find $y_{CP}=(1.31\pm 0.32({\rm stat.})\pm 0.25({\rm syst.}))%$, 3.2 standard deviations from zero. We also search for a CP asymmetry between $D^0$ and $\bar{D}^0$ decays; no evidence for CP violation is found. These results are based on 540 fb$^{-1}$ of data recorded by the Belle detector at the KEKB $e^+e^-$ collider.